Riding my non-winter bike for the first time in a while I was looking at some bits that I haven't considered since I built it up in April - chainring bolts, pedals, etc.

I know lots of people just love to take everything apart and put it back together, but for stuff that bolts on and stays there, is there any reason to actually dismantle, clean and reinstall stuff that seems to be working fine? Stuff like cranks, bb, pedals, and anything else that doesn't require regular attention like tires and the chain.

Besides having a gleaming bike I mean. When I last took the pedals off my mtb, the threads came out a clean and greased as when I'd installed them, but looking at some dirt accumulated on the insides of the pedal threads on my "nice" cranks I got to thinking.

Non-cartridge BB's, pedals, and hubs should be repacked occasionally, but that's not really your question. Dirt really can't get into parts that are screwed together, any dirt you see on threads got there when you took the thing apart. Disassembly for diassembly's sake is pointless, but a lot of things are easier to clean and maintain if you take them apart a bit.